Tooth whitening is becoming more common as improved tooth whitening technologies are developed. At present two forms of self applied tooth whitening procedures predominate. In one form, a formulation including a tooth whitening active is supplied on a thin flexible substrate or strip, which is then applied to the teeth. The flexible backing layer protects the active and permits the active to contact the teeth long enough to have a whitening affect. Typically the tooth whitening strip is left in contact with the teeth for about 30 minutes or more. The use of clear strips permits the user to be active during the teeth whitening procedure. However, once the tooth whitening step is complete, it is necessary to remove the remaining substrate and dispose of it, which is awkward. Examples of this type of tooth whitening product are found in the following patents:
U.S. Pat. No. 5,879,691 issued Mar. 9, 1999
U.S. Pat. No. 5,891,453 issued Apr. 6, 1999
U.S. Pat. No. 5,894,017 issued Apr. 13, 1999
U.S. Pat. No. 5,989,569 issued Nov. 23, 1999
U.S. Pat. No. 6,045,811 issued Apr. 4, 2000
U.S. Pat. App. No. 2002/0006388 published on Jan. 17, 2002
U.S. Pat. App. No. 2002/0012685 published on Jan. 31, 2002
U.S. Pat. App. No. 2002/0187112 published on Dec. 12, 2002
U.S. Pat. App. No. 2003/0044361 published on Mar. 6, 2003
U.S. Pat. No. 6,582,708 issued Jun. 24, 2003
U.S. Pat. App. No. 2003/0129148 published on Jul. 10, 2003
U.S. Pat. App. No. 2003/0194382 published on Oct. 16, 2003
U.S. Pat. App. No. 2003/0211056 published on Nov. 13, 2003
The second predominant form of tooth whitening is in the form of brush-on tooth whitening products. Brush-on products typically take the form of a viscous gel, which is packaged in a small bottle, with an accompanying brush-on applicator. Essentially what is required is to stretch the lips away from the teeth and brush on the gel, which includes a teeth whitening active. In order to be efficacious, the tooth whitening gel needs to adhere to the tooth surface and must be carefully applied only to the tooth enamel and not to any mucosal membrane such as the gums. The active requires the person applying the product to keep their mouth open and their soft tissue away from their teeth for a recommended amount of time, usually around 30 seconds. In brush-on tooth whitening products there is no barrier to protect the mucosal membranes after the lips are closed; this has the potential to both cause soft tissue irritation and displace whitening active from the tooth surface.
Physiologically acceptable consumable films are known including an antimicrobial effective amount of essential oils, as taught by U.S. Patent Application 2003/0008008. This patent application does not teach tooth whitening.
More recently, an erodible strip has been proposed as a means of carrying a tooth whitening active in the mouth. An example is disclosed in the U.S. application 2004/0062724 which is directed to an erodible film for treating the surfaces of teeth. This patent application discloses a thin flexible bi-layer or multi-layer of film which when applied to teeth surfaces adheres and delivers an active compound to the underlying surface. In the mouth the film erodes at a predetermined rate. The amount of time that the active agent remains in contact with the teeth surfaces is controlled by the rate of erosion of the backing layer, which is in turn controlled by the composition of the backing layer of the composite film. This application teaches that the erosion or residence time can be regulated one half hour to three hours depending on the desired therapeutic or cosmetic appearance. The erosion is controlled by use of at least one hydrophobic polymer or a combination of hydrophilic and hydrophobic polymers. However, having the film in contact with the teeth for such a long period of time makes use of the product awkward. More specifically during the time the film is in contact with the teeth the person may not be able to eat, drink or the like, for fear of affecting the tooth whitening process.
U.S. patent application 2003/0228264 discloses a tooth whitening strip made from a dissolvable matrix. The tooth whitening material may be contained in a pocket or mixed in with the dissolvable matrix. Various types of matrix are taught, but there is no teaching how to control the rate of dissolution of the matrix.
What is desired is a method of tooth whitening using a thin strip which is fast, easy to use and reliable, having a known and predetermined dissolution rate. Most preferably, such a tooth whitening system would enable teeth to be whitened by a predetermined amount in a period of up to approximately five minutes. After this time, the majority of tooth whitening active will be dissolved and the user will have little or no sensation of the product remaining in the mouth or on the tooth surface. Further, it is believed important that the manufacturing processes ensure that there is a viable amount of stable tooth whitening active provided.